1. Field of the Invention
This invention is directed to an agricultural tillage implement which includes a center portion hingedly attached to a pair of wing portions, and more particularly to such an implement in which the center portion includes a lifting and self-leveling mechanism and the wing portions each include a gauge wheel linked to a separate lifting and self-leveling mechanism so that the entire implement is level from front to back and from side to side.
2. Description of the Related Art
Agricultural tillage implements, such as plows, cultivating discs, etc., have gotten increasingly larger and more sophisticated in recent years. Most such implements are equipped with multiple rows of tillage tools in order to save time and fuel during tillage operations. As these implements have gotten wider, a problem has arisen in transporting the implements down a roadway, for example. In order to address this problem, wider tillage implements have been constructed with a wheel supported center section and one or more hinged wing sections which are adapted to fold over the center section while it is being transported in order to narrow the profile of the implement.
A further problem associated with large tillage implements is that, in order to assure uniform penetration of soil by the tillage tools, the implements must be leveled from front to back.
A number of prior art self-leveling systems have been developed for leveling agricultural implements to provide uniform tillage depth. An example is the applicant's U.S. Pat. No. 4,606,413 which teaches a hydraulic lift with self-leveling mechanism for an implement center portion. The self-leveling system includes a bell crank pivotally attached to a hitch member. As the implement frame is raised or lowered via a hydraulic lift cylinder, the force of the lifting mechanism is transferred about the hitch member. A pair of frame lift linkages are connected from a retractable piston in the cylinder to respective ground engaging wheels via a torque tube and respective lift arms. As the hydraulic cylinder piston is extended, the lift linkages are pushed forward, causing the torque tube to pivot the lift arms and attached wheels downward, thus raising the implement frame with respect to ground level. Conversely, as the piston is retracted, the lift arm is pivoted upward, thus lowering the implement frame. U.S. Pat. No. 4,606,413 is hereby incorporated herein by reference.
With wider implements, it is also important that they be leveled from side to side. This is particularly true of implements with hinged wing sections. In such implements, where the wings include separate ground engaging wheels, both the center section and the wings should be leveled, both from front to back and with respect to each other via the respective wheels. In addition, prior art implements have generally not been adequately supported by wheels at the front corners of the wings. Accordingly, this inadequate support, along with vibration and bouncing of the implement as it traverses the ground have meant that the wing portions flex relative to the center portion. This means that the tillage tools, particularly on the front of the wings, often run at different depths than the other tools, even when the implement is "leveled" via the self-leveling mechanism of the center portion.
It is clear then, that a need still exists for a self-leveling system for a hinged wing tillage implement which provides adequate corner support for the wings as well as leveling the center portion and the wings from front to back and from side to side.